High-bulk polyacrylonitrile yarn

ABSTRACT

Dyed, highly-bulked yarns of polyacrylonitrile fibers are produced by treating the yarns below their melting point with an acid liquor which in addition to a cationic dye also contains a compound which swells and/or starts dissolving the fibers. After this treatment, the yarns are subjected to a damp heat treatment at temperatures of at least 98* preferably in the range from 98* to 100*.

United States Patent [191 Amend HIGH-BULK POLYACRYLONITRILE YARN [75] Inventor: Werner Amend, Wuppertal-Barmen,

Germany [73] Assignee: Hacoba-Textilmaschinen GmbH &

Co. KG, Wuppertal-Barmen, Germany [22] Filed: Dec. 26, 1972 211 App]. No.1 318,560

1 Related U.S. Application Data [63] Continuation of Ser. No. 90,034, Nov. 16, 1970,

abandoned.

[52] U.S. Cl. 8/172; 8/93; 8/173; 8/175;8/177R [51] Int. Cl D06p 5/06 [58] Field of Search 8/93, 172, 175, 177 AB, 8/177 R, 173

[56] References Cited UNITED STATES PATENTS 2,404,718 7/1946 l-loutz 260/308 2,953,420 9/1960 3,051,736 8/1962 3,114,588 12/1963 Lewis 8/177 3,116,103 12/1963 Gamlen et a1. 8/18 51 May 13, 1975 3,117,831 1/1964 Mautner 8/175 3,529,927 9/1970 Ulrick 8/173 3,558,260 1/1971 Hermes 8/21 FOREIGN PATENTS OR APPLICATIONS 891,907 3/1962 United Kingdom 8/177 OTHER PUBLICATIONS Ham, 1nd. & Eng. Chem., Vol. 46, No. 1, pp. 390-392.

Neary et a1., Amer. Dyestuff Reporter, V01. 46, No. 17, pp. 625-633.

Primary ExaminerBenjamin R. Padgett Assistant Examiner-Peter A. Nelson Attorney, Agent, or Firml(ar1 E. Ross; Herbert Dubno 1 Claim, No Drawings HIGH-BULK POLYACRYLONITRILE YARN This is a continuation of application Ser. No. 90,034, filed Nov. 16, l970, now abandoned.

FIELD OF INVENTION The invention relates to high-bulk polyacrylonitrile yarn and a method of making same.

BACKGROUND OF THE INVENTION It is known to dye and bulk polyacrylonitrile yarns which consist of mixtures of shrinkable and nonshrinking fibers. Cationic dyes in acid media are used as the coloring substances. There are two usual methods for the manufacture of dyed and bulked yarns.

In the first method, the non-bulked yarns brought from the spinning mill to the cops are first made into larger coils (crosscoils, bobbins) and are then reeled into strands, after which they are dyed for 2 to 4 hours in a suspending apparatus, using a liquor ratio in the range from 1:30 to 1:60 at a temperature in the range of 75 to 106 C, whereby either the dye bath must be slowly heated (at about 05 C per minute) from 75 to 100C, or in a low-pressure apparatus to 106C or, in the case of a temperature in the range from 80 to 100C, this must be maintained for 45 to 90 minutes and then left at 100C or 106C for at least minutes.

It is a feature of both of these variations of the method that the yarn must be heated to 100C or 106C for a specific time so that the shrinkable portion of the yarn can shrink and the bulking effect can thus be achieved. After heating to 100 or 106C, in both these variations, the liquor must be slowly cooled (about 1C per minute) so that the bulking effect and feel of the fabric are retained. After the usual secondary treatment, the strands must then be converted into coil form for subsequent use, e.g. for knitting.

Apart from the fact that this method is uneconomical due to the high liquor ratio, the expensive reeling of coiled shapes into strands and the particularly expensive rewinding of strands into coils, it also has the disad vantage that the yarn is distorted by the movement of the liquor and that the positions of the strands on the bars of the dyeing machine become clearly marked.

In the second method, the yarns from the spinning mill on the cops are wound into a special form, namely such that a coiled body is obtained which enables the yarns to be shrunk during the dyeing process at 75 to 106C without a solid casing. Apart from the fact that special and unusual winding apparatus is required, this method also has the disadvantage that the cross-over points of the threads are clearly marked. This method is therefore only used in practice for simple (i.e. untwisted) and fine yarns. The second variation of the first method is also possible with this method. For subsequent treatment, the yarns must generally be wound on to the user spools.

In both methods, it is impossible to dye the yarns below the melting point of the threads (in technical terms, the glass transformation point or glass transition temperature-see pg. ll61l7 of WHITTING- TONS DICTIONARY OF PLASTICS, First Edition, Technomic Pub. Co., 1968), which generally lies at about 80C in fibers which are usually dry-spun and about 70C in fibers which are usually wet-spun.

It is furthermore already known to dye and bulk knitted articles, e.g. pullovers or sleeves, of polyacrylonitrile yarns, in which the yarn consists of a mixture of shrinkable and non-shrinking fibers, with cationic dyes, by treating them for 2 to 4 hours with an acid liquor which contains the dissolved cationic dye, at a temperature in the range from to 100C, whereby either the liquor is slowly heated (about 05 per minute) or in the case ofa temperature in the range of to C, this is maintained for 45 to 90 minutes and the bath is then heated to C and is retained at this temperature for at least 15 minutes. The treatment of the shaped articles takes place in paddle-dyeing machines, but in order to avoid distortion, the articles must be sewn into pouches. In order to overcome this difficulty, the shaped articles are treated on specially developed apparatus which does not have paddles but uses nozzles to move the liquor.

For smooth finishing, after treatment with the dyeing liquor and the usual rinsing, finishing and drying steps, the shaped articles are wound onto formers and are steamed at 98 to 100C. Since yarn shrinkage of up to about 25% occurs in the shaped articles in the event of treatment with the hot to boiling dyeing liquor visible different final dimensions of the shaped articles often result. Moreover, strong warping of the shaped articles cannot be avoided and unusable merchandise is obtained.

It is also known to dye and bulk flat sheet-like textile material of polyacrylonitrile yarns which consist wholly or partially of a mixture of shrinkable and nonshrinking polyacrylonitrile fibers in acid baths with cationic dyes, whereby the treatment of the textile mate rial takes place for example on a jigger, beam dyeing machine, winch machine or star-frame dyeing machine and the processing liquors likewise have temperatures above the glass transformation point. In this method, the flat sheet-like textile material contracts so much that a satisfactorily uniform dye penetration of the yarn is not possible. Furthermore, distortions and warping occur through the practically uncontrollable shrinkage and the mechanical stresses. Also the feel of the fabric is impaired by the distortion of the yarn; a flattened yarn which is crushed at the cross-over points is obtained.

OBJECT OF THE INVENTION It is the object of the invention to provide an improved high-bulk dyed polyacrylonitrile yarn and a method of making same.

SUMMARY OF THE INVENTION It has now been found that dyed, highly-bulked yarns of polyacrylonitrile fibers can be produced by treating the yarns below their melting point with an acid liquor which, in addition to a cationic dye, also contains a compound which swells and/or starts dissolving the fibers and, after the treatment, subjecting the yarns to a damp heat treatment at temperatures of at least 98C, preferably in the range of 98 to 100C.

SPECIFIC DESCRIPTION With the method of the invention, the temperature of the dyeing liquor always lies beneath the glass transformation point of the fibers and generally amounts to 40C to 79C, preferably 60C to 75C, whereby the lower temperatures are preferably chosen for wet-spun fibers and the higher temperatures for dry-spun fibers. The processing time with the dyeing bath amounts to 10 to 90 minutes, preferably 30 to 60 minutes.

The cationic dyes used are sufficiently known, as are the usual liquor additives, such as acetic acid which are used for coloring the polyacrylonitrile yarns.

After the treatment with the dyeing liquor. rinsing and finishing is carried out in the usual manner.

With the method according to the invention, yarns which are wound on to spools can be subjected to treatment with the acid dyeing liquor and then rinsed, finished, centrifuged or drawn off in the usual way. Thereafter, the wound damp yarns are rewound onto the user spools, which is necessary for subsequent treatment whereby during the rewinding process, the yarns are subjected while free of tension to the damp-heat treatment. They thereby pass through a zone in which they are heated, preferably at temperatures in the range of 98 to 100C. In this heating zone, the necessary temperature can be produced for example by means of steam, infrared rays, microwaves or hot air. The length of heating depends on the residual moisture of the yarns and on the amount of dye applied. The heating times are from 2 to 15 minutes, preferably from 4 to 10 minutes, but heating times of 5 to 20 seconds may also produce a useful effect. The rate of flow depends on the size of the heating zone. The yarn preferably leaves the heating zone in the dry state. In order to guarantee a bulking effect, the yarn must be passed, free of tension, through the heating zone according to one of the conventional methods, e.g. by way of a wire cloth or by cuttling in a chamber-like heating zone.

According to a further feature of the invention, the yarns are first processed into shaped articles and then subjected to treatment with the acid dyeing bath and afterwards place on molds or formers for the heat treatment. The shaped articles are thus placed on the molds after finishing and possibly centrifuging and are then steamed, whereby the shaped articles are shrunk to the desired shape.

Moreover, the yarns to be treated according to the invention can also be subjected to the dyeing process in the form of flat sheet-like material, e.g. as fabric, knitted texture, knitting or sections of tubular fabrics or circular knitted goods. In this form, these textile materials are steamed for seconds to 10 minutes, preferably from 30 seconds to 5 minutes. Steaming is carried out on the usual steaming apparatus, such as a screen belt or perforated drum steamer, or a steamcoated tenter frame, and can be so arranged that specific final dimensionsof the textile fabric are obtained.

The compounds required for the method according to the invention to swell and/or start to dissolve the fibers in an aqueous medium are already partly known as such from technical literature, but can however easily and quickly be discovered by the expert. In order to find out, a yarn sample of about 10 g need only be treated in 200 cc of a liquor for 45 minutes at 65C, wherein the liquor contains, per liter of water, 1 cc of 60% acetic acid, 0.5 g of the yarn dye material including Color Index No. 48055 in the usual form and condition and 60 g of the substance to be tested. As opposed to a control sample (without a swelling or solvent substance), the yarn must be dyed twice as deep. It is clear to the expert that with this test a large number of substances can be tested next to one another at the same time, whereby in addition the minimum amount of material required can be ascertained. If solid products which are insoluble in water are to be tested, they are first dissolved in an organic solvent chosen such that an excess of solvent is not harmful; with aliphatic compounds, in e.g. aliphatic alcohols such as methanol, ethanol or even polyglycols, with aromatic compounds, generally in benzyl alcohol to which methanol is added in the same amount as the benzyl alcohol and about 10% by weight of a conventional nonionic emulsifier is added to these solutions. A general addition of methanol in a ratio of 1:1 and of a nonionic commercial emulsifier in the ratio of 1:0.1 is preferable however, particularly when the tester does not first want to check the exact solubility of the products in the usual technical books. In the case of liquid compounds which are insoluble in water, a conventional nonionic emulsifier in the ratio 1101 to 1:08 is added to the products, preferably with an alcohol such as methyl or ethyl alcohol in the ratio of 1:1.

As regards swelling or dissolving compounds, the following 52 in are preferred:

Diesters of carbonic acid, especially cyclic diesters of carbonic acid with glycols, in particular with ethylene and propylene glycols, whose carbonic diesters are referred to technically as ethylene or propylene carbonate, aliphatic, cycloaliphatic and aromatic mono-and dinitriles, which if required can be substituted and moreover, can contain heteroatoms, such as for example oxygen and nitrogen, between two carbon atoms; by way of example, acetonitrile, propionitrile, benzyloxypropionitrile O ca oca ca cu).

phenylacetonitrile, benzonitrile, succinonitrile, azelaic dinitrile and phthalonitrile.

Mononitriles substituted with a phenyl group are preferably used. Benzyloxypropionitrile is particularly suitable as regards efficiency and possible toxicity.

It is obvious that mixtures of these compounds may also be used. As a rule, a solution must first be prepared from those compounds which are solid and insoluble in water and an emulsifier is then added to the solution. With aliphatic compounds, an aliphatic monohydric or polyhydroc alcohol, e.g. methanol, ethanol or glycol, is preferably used as the solvent and, with aromatic compounds, benzyl alcohol is preferably used, to which methanol is added after the dissolving process in the ratio of benzyl alcohol to methanol of 1:4 to 4:1 parts by weight. Only nonionic products, particularly the ethoxylated products of .alkylphenols, and moreover the ethoxylated products of fatty acid esters, fatty alcohols and fatty amines and the alkylpolypropylene glycolpolyglycol ethers, are suitable as emulsifiers. Furthermore, polyalkylene oxides, e.g. polyglycols or mixed products of unsubstituted polypropylene oxide and polyethylene oxide units are suitable as emulsifiers, for, at least, the emulsifying effect of nonionic emulsifiers is clearly improved by the addition of such compounds.

a ratio of 5:1 though a higher amount does not have a 5 disadvantageous effect. Also, an addition of alcohol has a particularly favorable effect. For economical reasons, the additive should normally not be higher than 1:1, 3 to 60 g and, generally, 5 to 40 g par liter of the compounds which swell and/or dissolve the fibers are added to the dye bath. The amount to be added depends on the amount of dye used, the dye temperature and the type of fiber; higher amounts of dye, lower temperatures and dry-spun fibers require higher quantities and vice versa.

As contrasted with the most common method, namely treatment in strand form with yarns of the instant invention the expensive unwinding and the even more subsequent rewinding of the strands are dispensed with. The spool losses are much less with the method according to the invention and the kink-free lengths are longer. Moreover, high liquer ratios are avoided. As destinct from the treatment on special spools, with the method according to the invention, only the normal winding machines are required and, furthermore, twisted and coarse yarns may also be treated. As opposed to all the known methods, there is in addition the great advantage that no marking spots occur and the swelling effect is more favorable since a voluminous yarn results.

Passing the yarn through the heating zone does not represent an additional working step for even with the known method, drying and rewinding also take place.

If the yarns are in the form of shaped articles, the method according to the invention has the advantage over the known methods in that no special dyeing machines are required, but processing can take place in the paddle machine without the articles having to be sewn into sacks, since distortion and warping do not occur.

[f the yarns are in the form of flat, sheet-like textile material, the method according to the invention has the advantage that the yarns do not become flattened or crushed at the crossover points, and furthermore, that distortions and warping do not occur, but a very good dye penetration is obtained.

It is surprising that a method like that of the invention is possible; when dyeing polyacrylonitrile fibers with cationic coloring substances, in order to avoid any irregularities, long processing times with very long heating up times are required and special compounds, socalled retarders, are added with in addition retard the taking up of the coloring substances, while the method according to the invention succeeds using only short processing times, temperature stability and no retarders. However no irregularities occur. It is furthermore surprising that compounds which have a swelling and- /or dissolving effect on the fibers in the method according to the invention have no adverse influence on the technological properties of the fibers, particularly the breaking tension. Furthermore, it is stated in technical literature that it is not possible to dye polyacrylonitrile fibers beneath the melting point of the fibers (glass transformation point). Thus the expert is considerably prejudiced against the practicability of a method of the type according to the invention.

SPECIFIC EXAMPLES EXAMPLE 1 A 600 g cross-coiled spool of polyacrylonitrile yarn which consisted of shrinkable and non-shrinking wetspun fibers and had a yarn thickness of Nm 22/2*, was treated with a liquor in the ratio of 1:10 for 60 minutes at 65C on a cross-coil machine, the liquor containing, in 1 liter of water, 1 g of dyestuff (A), Color Index No. 48055 in the usual form and quality, 1 cc of 60 acetic acid and 30 g propylene carbonate. *The thickness measurement Nm 22/2 indicates a double twist (/2) and a specific length of 22 meters per gram.

It was then hot and cold rinsed, finished and centrifuged. The yarn was then continuously cuttled on an endless screen belt, treated with saturated steam at 100C and then dried by means of hot air and wound on to a cone. A highly bulked, voluminous, dark yellow yarn without any markings or irregularities was obtained.

EXAMPLE 2 Shaped articles weighing 10 kg and consisting of polyacrylonitrile yarns which comprises shrinkable and non-shrinking wet-spun polyacrylonitrile fibers were treated with liquor in a ratio of 1:50 for 60 minutes at 65C in a paddle dyeing machine, the liquor containing in 1 liter of water 0.2 g of the following dye:

n n 0 Me n in the usual form and quality;

1 cc of 60% acetic acid,

5 g benzyloxypropionitrile dissolved in 0.4 g benzyl alcohol 0.8 g methanol 1.0 g of a polyglycol ester with 10 mo] ethylene oxide 0.8 g of an adduct of propylene oxide and ethylene oxide of average molecular weight 1500.

It was then hot and cold rinsed, finished and dried. The shaped articles were then placed on suitable for mers and steamed for 4 minutes.

EXAMPLE 3 A fabric of polyacrylonitrile yarn which consisted in the warp of Nm /2 non-shrinking polyacrylonitrile yarn and in the weft of Nm 60/2 polyacrylonitrile yarn with shrinking and non-shrinking fibers, woven in a width of 1.60 m, was treated on a jigger in a liquor ratio of 1:5 for 45 minutes at 65C with a liquor which contained in 1 liter:

2 g of dyestuff, Color Index No. 48020 I claim:

1. A method of making high-bulk polyacrylonitrile yarn covered with cationic dyes, which comprises the steps of treating unbulked polyacrylonitrile yarn in a bath at a temperature beneath C and its glass transition temperature with an aqueous acid liquor containing a cationic dye and benzyloxypropionitrile as a polar organic compound which swells or solubilizes the fibers of said yarn, and thereafter subjecting the yarn to damp heat treatment at a temperature of substantially 98C to 100C, the yarn being subjected to the treatment with the aqueous acid liquor while coiled on spools, is then rinsed, finished and centrifuged and is finally rewound from the spools on to user spools while being maintained free from tension during the rewinding process during the damp heat treatment for a period of 5 seconds to 15 minutes. 

1. A METHOD OF MAKING HIGH-BULK POLYACRYLONITRILE YARN COVERED WITH CATIONIC DYES, WHICH COMPRISES THE STEPS OF TREATING UNBULKED POLYACRYLONITRILE YARN IN A BATH AT A TEMPERATURE BENEATH 70*C AND ITS GLASS TRANSITION TEMPERATURE WITH AN AWUEOUS ACID LIQUOR CONTAINING A CATIONIC DYE AND BENZYLOXYPROPIONITRILE AS A POLAR ORGANIC COMPOUND WHICH SWELLS OR SOLUBILIZES THE FIBERS OF SAID YARNS, AND THEREAFTER SUBJECTING THE YARN TO DAMP HEAT TREATMENT AT A TEMPERATURE OF SUBSTANTIALLY 98*C TO 100*C, THE YARN BEING SUBJECTING TO THE TREATMENT WITH THE AQUEOUS ACID LIQUOR WHILE COILED ON SPOOLS, IS THEN RINSED, FINISHED AND CENTRIFUGED AND IS FINALLY REWOUND FROM THE SPOOLS ON TO USER SPOOLS WHILE BEING MAINTAINED FREE FROM TENSION DURING THE REWINDING PROCESS DURING THE DAMP HEAT TREATMENT FOR A PERIOD OF 5 SECONDS TO 15 MINUTES. 